*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: #1a1a2e;
  color: #e0e0e0;
  min-height: 100vh;
}

.app {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.5rem 1rem;
}

h1 { font-size: 1.8rem; color: #fff; margin-bottom: 0.25rem; }
.subtitle { color: #888; margin-bottom: 1.5rem; }
.repo-link { color: #666; text-decoration: none; }
.repo-link:hover { color: #aaa; text-decoration: underline; }

/* ── Controls bar ──────────────────────────────────────────────────── */

.controls {
  background: #16213e;
  border-radius: 12px;
  padding: 1.25rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  align-items: flex-end;
  margin-bottom: 1.5rem;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.control-group label {
  font-size: 0.85rem;
  color: #aaa;
}

input[type="number"] {
  width: 90px;
  padding: 0.4rem 0.5rem;
  border: 1px solid #333;
  border-radius: 6px;
  background: #0f0f23;
  color: #fff;
  font-size: 0.95rem;
}

input[type="file"] { font-size: 0.9rem; color: #ccc; }

input[type="range"] {
  width: 160px;
  accent-color: #3578d1;
}

select {
  padding: 0.4rem 0.5rem;
  border: 1px solid #333;
  border-radius: 6px;
  background: #0f0f23;
  color: #fff;
  font-size: 0.95rem;
  min-width: 180px;
}

.algo-desc {
  font-size: 0.78rem;
  color: #777;
  max-width: 300px;
  margin-top: 0.2rem;
}

button {
  padding: 0.5rem 1.5rem;
  border: none;
  border-radius: 6px;
  background: #0f3460;
  color: #fff;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background 0.2s;
  align-self: flex-end;
}

button:hover:not(:disabled) { background: #1a5276; }
button:disabled { opacity: 0.4; cursor: not-allowed; }

/* ── Preview panels ────────────────────────────────────────────────── */

.top-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

.preview-panel {
  background: #16213e;
  border-radius: 12px;
  padding: 1rem;
}

.preview-panel h2 {
  font-size: 1rem;
  margin-bottom: 0.5rem;
  color: #ccc;
}

.canvas-wrap {
  background: repeating-conic-gradient(#2a2a3e 0% 25%, #1e1e32 0% 50%) 0 0 / 20px 20px;
  border-radius: 8px;
  min-height: 160px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: auto;
  padding: 0.75rem;
}

canvas {
  image-rendering: pixelated;
  image-rendering: crisp-edges;
}

.zoom-bar {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  margin-bottom: 0.4rem;
}

.zoom-btn {
  padding: 0.2rem 0.6rem;
  font-size: 0.85rem;
  min-width: 0;
  align-self: auto;
}

.zoom-fit { margin-left: 0.3rem; font-size: 0.78rem; }

.zoom-label {
  font-size: 0.85rem;
  color: #aaa;
  min-width: 2.5rem;
  text-align: center;
}

.dimensions {
  font-size: 0.8rem;
  color: #666;
  margin-top: 0.5rem;
}

.download-btn {
  display: inline-block;
  margin-top: 0.5rem;
  padding: 0.35rem 1rem;
  background: #0f3460;
  color: #fff;
  border-radius: 6px;
  text-decoration: none;
  font-size: 0.85rem;
  cursor: pointer;
}

.download-btn:hover { background: #1a5276; }

/* ── Color Transform Section ───────────────────────────────────────── */

.color-section {
  margin-top: 0.5rem;
}

.color-section > h2 {
  font-size: 1.2rem;
  color: #fff;
  margin-bottom: 1rem;
}

.cluster-controls {
  background: #16213e;
  border-radius: 12px;
  padding: 1rem 1.25rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  align-items: flex-end;
  margin-bottom: 1.5rem;
}

.cluster-count {
  font-size: 0.85rem;
  color: #aaa;
  align-self: flex-end;
  padding-bottom: 0.35rem;
}

.cluster-warning {
  width: 100%;
  font-size: 0.75rem;
  color: #886;
  margin-top: 0.1rem;
}

.mapping-hint {
  font-size: 0.72rem;
  color: #667;
  margin-bottom: 0.5rem;
}

/* Bottom 3-column layout */

.bottom-row {
  display: grid;
  grid-template-columns: 1fr minmax(240px, 300px) 1fr;
  gap: 1.25rem;
  align-items: start;
}

/* ── Mapping Panel ─────────────────────────────────────────────────── */

.mapping-panel {
  background: #16213e;
  border-radius: 12px;
  padding: 1rem;
  max-height: 480px;
  display: flex;
  flex-direction: column;
}

.mapping-panel h3 {
  font-size: 0.9rem;
  color: #ccc;
  margin-bottom: 0.4rem;
}

.cluster-list {
  overflow-y: auto;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.cluster-item {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 5px 8px;
  border-radius: 6px;
  cursor: pointer;
  transition: background 0.15s;
  font-size: 0.82rem;
  border: 2px solid transparent;
}

.cluster-item:hover {
  background: #1e2d50;
}

.cluster-item.highlight {
  border-color: #3578d1;
  background: #1a2e55;
}

.cluster-swatch, .bead-swatch {
  width: 22px;
  height: 22px;
  border-radius: 4px;
  border: 1px solid rgba(255,255,255,0.15);
  flex-shrink: 0;
}

.cluster-arrow {
  color: #555;
  font-size: 0.8rem;
}

.bead-tag {
  color: #aaa;
  font-size: 0.78rem;
  min-width: 28px;
}

.cluster-px {
  color: #555;
  font-size: 0.72rem;
  margin-left: auto;
  white-space: nowrap;
}

/* ── Bead Picker Popover ───────────────────────────────────────────── */

.bead-picker {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: #12192e;
  border: 1px solid #333;
  border-radius: 14px;
  padding: 1.25rem;
  z-index: 1000;
  max-width: 520px;
  width: 92vw;
  max-height: 80vh;
  overflow-y: auto;
  box-shadow: 0 8px 40px rgba(0,0,0,0.6);
}

.picker-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.picker-compare {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
}

.picker-swatch {
  width: 32px;
  height: 32px;
  border-radius: 6px;
  border: 1px solid rgba(255,255,255,0.2);
}

#picker-tag {
  color: #aaa;
  font-size: 0.85rem;
}

#picker-close {
  background: none;
  border: none;
  color: #888;
  font-size: 1.3rem;
  cursor: pointer;
  padding: 0.2rem 0.5rem;
  align-self: auto;
}

#picker-close:hover { color: #fff; }

.picker-group-label {
  font-size: 0.72rem;
  color: #666;
  padding: 6px 2px 2px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.picker-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}

.picker-cell {
  width: 28px;
  height: 28px;
  border-radius: 4px;
  border: 2px solid transparent;
  cursor: pointer;
  transition: border-color 0.1s, transform 0.1s;
  position: relative;
}

.picker-cell:hover {
  border-color: #fff;
  transform: scale(1.15);
  z-index: 1;
}

.picker-cell.selected {
  border-color: #3578d1;
  box-shadow: 0 0 0 1px #3578d1;
}

/* Backdrop */
.picker-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.4);
  z-index: 999;
}

/* ── Instructions ─────────────────────────────────────────────────── */

.instructions {
  background: #16213e;
  border-radius: 12px;
  padding: 0.85rem 1.25rem;
  margin-bottom: 1rem;
  font-size: 0.88rem;
  color: #aaa;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.instructions strong { color: #ccc; }

/* ── Assembly Instruction Section ─────────────────────────────────── */

.instruction-section {
  margin-top: 1.5rem;
}

.instruction-section > h2 {
  font-size: 1.2rem;
  color: #fff;
  margin-bottom: 1rem;
}

#instruction-output {
  margin-top: 1rem;
  overflow-x: auto;
  background: #fff;
  border-radius: 8px;
  padding: 0.5rem;
}

#instruction-canvas {
  display: block;
  max-width: 100%;
  height: auto;
  image-rendering: auto;
}

/* ── Responsive ────────────────────────────────────────────────────── */

@media (max-width: 960px) {
  .bottom-row {
    grid-template-columns: 1fr 1fr;
  }
  .mapping-panel {
    grid-column: 1 / -1;
    order: -1;
    max-height: 300px;
  }
}

@media (max-width: 700px) {
  .app { padding: 1rem 0.5rem; }

  .top-row, .bottom-row {
    grid-template-columns: 1fr;
  }

  .controls {
    flex-direction: column;
    align-items: stretch;
  }

  .controls .control-group {
    width: 100%;
  }

  .controls select { min-width: 0; width: 100%; }

  input[type="range"] { width: 100%; }

  .mapping-panel {
    grid-column: auto;
    order: 0;
    max-height: 260px;
  }

  .canvas-wrap { min-height: 120px; }

  .bead-picker {
    width: 96vw;
    max-height: 85vh;
    padding: 1rem;
  }

  .picker-cell {
    width: 32px;
    height: 32px;
  }
}